This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-187913, filed Jul. 1, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a lens-equipped film unit capable of taking a photograph of appropriate density-in any photographing environment.
Various types of lens-equipped film units each comprising a unit body wherein simple photographing means such as a photographic lens, a shutter and a film winding up apparatuses are accommodated; and an unexposed photographic film charged in the unit body at the time of manufacturing thereof, are being marketed. The lens-equipped film units include one having a built-in strobe for enabling photographing in the nighttime or a dark place such as the interior of a building.
The lens-equipped film unit having a built-in strobe is so designed that a combination of shutter speed, stop down value and film sensitivity are fixed so as to cope with the brightness during the daytime and that, at the time of photographing in a dark place such as the interior of a building, appropriate strobe photographing is carried out as for a main subject located at a distance of, for example, about 1 to 4 m.
However, when strobe photographing is performed indoors or outdoors in the nighttime with the use of the conventional lens-equipped film unit having a built-in strobe, the background suffers from considerable under-exposure while a main subject such as a human suffers from over-exposure with the result that satisfactory prints cannot be obtained. One measure for solving this problem can be provided by the method disclosed in Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 10-333287 wherein the densities of a main subject and background are balanced by using a film of ISO 600 or more and by, only at the time of strobe photographing, setting the f-number of aperture at F8 or less. However, this method has a grave drawback in that when no strobe is used at the time of photographing indoors or in the nighttime, no quality improvement can be attained. When a strobe is used outdoors in the daytime, over-exposure exceeding the film latitude occurs to thereby lower the print quality.
JP-A-10-333287 discloses a method of changing a shutter speed, interlocked with a strobe switch. However, ensuring the precision of shutter speed switching is difficult from the viewpoint of appropriate manufacturing, and a low-speed shutter invites camera movement and other causes of image quality lowering to thereby lead to deterioration of the sharpness of photographic prints.
Further, JP-A-10-260507 discloses a lens-equipped film unit characterized in that it is fitted with a photometric circuit capable of detecting the level of subject luminance relative to given. luminance and means for switching a stop down value- in accordance with the level of subject luminance detected by the photometric circuit. In this patent application specification, it is described that it is desirable to control the use or non-use of strobe flashing in accordance with the detection result of the photometric circuit. However, it has been found that the lens-equipped film unit disclosed therein has difficulty in taking a photograph in which the densities of main subject and background are well balanced, although the lens-equipped film unit enables reducing photographs of under-exposure as compared with the conventional lens-equipped film unit. The disclosed lens-equipped film unit has a further drawback that automatic strobe flashing occurs in circumstances where a strobe should not be used.
Still further, in the lens-equipped film unit disclosed in JP-A-9-5817, aperture control is performed by measuring a subject light quantity by means of a photoconductive element and operating an electromagnet in accordance with the measurement of the light quantity to thereby move an aperture plate furnished with an aperture opening. In the use of this lens-equipped film unit, exposure control can be automatically effected in conformity with the subject light quantity, so that any person can easily conduct photographing with appropriate exposure. However, this lens-equipped film unit, although realizing an improvement in over-exposure quality, is unsatisfactory in improving the density ratio of main subject to background when photographing a low-luminance subject.
The object of the present invention is to resolve the above problems and to provide a lens-equipped film unit which realizes an appropriate density ratio of main subject to background while photographing indoors or in the nighttime, and allows the user per se to make a selection as to the use or non-use of strobe flashing and which can provide preferable photographs within an appropriate exposure while photographing outdoors in the daytime, irrespective of the use or non-use of strobe. That is, the object of the present invention is to provide a lens-equipped film unit which can provide desirable photographs in any photographic environment.
Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.